In order to keep the swingable spindlehead as compact and light as possible, in the known machines of this class, the spindlehead contains mostly only the work spindle with the clamping devices, while the drive motor, the transmission and, if desired, the drive shaft which connects the transmission to the work spindle are arranged in nonswingable parts, thus for example the spindlehead carrier. A constructively simple solution results, when the spindlehead can be pivoted about an axis which lies in the direction of the drive shaft, since then the drive transmission can be formed by the drive shaft through a simple bevel gear pair. However, there are a number of types of machines in which it is necessary, for reasons which lie in the special division of the operating movements on the tool or workpiece, for a pivoting to occur about a drive shaft which is arranged transversely with respect to the spindlehead carrier.
A machine tool of this class is already known in which on a spindlehead carrier, which is movably supported in transverse direction, a spindlehead is pivotal continuously about an axis which lies transversely with respect to the drive shaft arranged in the spindle-head carrier (German OS No. 21 31 537). This results in an extremely complicated deflection of the driving movement from the drive shaft to the work spindle, which includes for example two bevel-gear pairs and three spur gears. The construction is therefore expensive and complicated and has moreover the disadvantage that the reversing gearing is loud and produces much damaging heat, which in turn influences the exactness of the machine.
It is the purpose of the present invention to provide a machine tool of this class, which can be substantially simpler in design and thus substantially more economical and also more exact.
This purpose is attained by the provision of a spindlehead which can be adjusted into several defined operating positions and that coupling devices for coupling of the work spindle with the drive shaft are associated with the work spindle and/or the drive shaft for each operating position. The recognition was thereby utilized that a continuous adjustability of the spindlehead is not utilized as a rule and cannot be utilized as a rule, since for example the exact adjustment of any desired swinging positions again demands a considerable expense with respect to the measuring, positioning and fixing means. Rather a few selected swinging positions which are to be fixed exactly for example through stops, are sufficient. In most cases, in connection with rotatable and swingable worktables, even only two positions, namely the horizontal and vertical position of the work spindle are sufficient.
In a first modification of the inventive solution, the input side of the work spindle is branched corresponding with the possible swinging positions, whereby the branches can each be aligned with respect to the drive spindle and can be coupled with same; in a second modification, the drive shaft is branched corresponding with the possible swinging positions and the work spindle is coupled with the various branches. The branches are formed preferably by stub shafts which are connected with the work spindle or the drive shaft through bevel gears and which are arranged angularly offset with respect thereto. The coupling means can then engage either on the stub shafts or the associated shaft or spindle end or can be formed by bevel gears in a different development of the invention, which bevel gears engage the above-mentioned bevel gears of the branches.
In a preferred exemplary embodiment having coupling means which engage the stub shafts, the stub shafts (or the spindle end itself) can be aligned in the various operating positions of the spindlehead, each coaxially with respect to the drive spindle and the drive shaft can be coupled with or uncoupled therefrom by longitudinal movement thereof.
In many cases, a spring-loaded clamping device is provided within the work spindle, which clamping device can be released by pressing onto an operating pin or the like which projects beyond the rearward end of the drive spindle. In such a case, it is inventively provided that the spindlehead can be swung into a toolexchanging position, in which the rearward end of the work spindle is provided in the area of an operating device which is arranged stationarily in the machine. In this manner, the inventive machine tool can also be equipped with an automatic tool changer .